Test Papers. These consist of paper which has been wetted thoroughly and uniformly with a solution of some appropriate substance, dried and cut into convenient strips, and is used to test, by its change of color, the presence of some other substance known to produce that change. This is effected by dipping a strip of the proper test paper into, or wetting it with, the liquor to be tested, and the effect noted.

4409. Brazil-wood Test Paper

4409.    Brazil-wood Test Paper. Made by preparing the paper with a decoction of Brazil-wood. Alkalies turn it purple or violet; strong acids, red.

4410. Buckthorn Test Paper

4410.    Buckthorn Test Paper. From a decoction of the berries; is reddened by acids.

4411. Cherry-juice Test Paper

4411.   Cherry-juice Test Paper. From the juice of cherries ; has the same properties as buckthorn paper.

4412. Dahlia Test Paper

4412.    Dahlia Test Paper. Made from an infusion of the petals of the violet dahlia (georgina purpurea); alkalies turn it green; acids, red; strong caustic alkalies turn it yellow. This is a very delicate test paper. The juice of elderberries will make a similar test paper.

4413. Indigo Test Paper

4413.     Indigo Test Paper. From a solution of indigo ; loses its color in contact with chlorine.

4414. Iodide of Potassium Test Paper

4414. Iodide of Potassium Test Paper. From a solution of it in distilled water; turned blue by an acidulated solution of starch.

4415. Starch and Iodine Test Paper

4415.    Starch and Iodine Test Paper.

Prepared by mixing starch paste with iodide of potassium ; turned blue by chlorine, ozone, and the mineral acids, and by the air containing them.

4416. Lead Test Paper

4416.    Lead Test Paper. From a solution of either acetate or diacetate of lead; used as a test for sulphuretted hydrogen and hydrosulphuret of ammonia, which turn it black.

4417. Blue Litmus Test Paper

4417.    Blue Litmus Test Paper. Triturate 1 ounce litmus in a wedgwood-ware mortar with 3 or 4 fluid ounces boiling water ; put the mixture into a flask, and add more boiling water until the liquid measures fully 1/2 pint; agitate it frequently until cold, then filter it; divide the filtered fluid into 2 equal portions, stir one portion with a glass rod dipped into very dilute sulphuric acid, repeating this until the liquid begins to be very slightly tinged red, then add the other portion and mix them thoroughly. Prepare the paper with this infusion. Acids turn it red; alkalies, green. The neutral salts of most of the heavy metallic oxides redden this as well as the other blue test papers that are affected by acids.

4418. Red Litmus Paper

4418.    Red Litmus Paper. Treat the whole of a blue infusion, made as above, with the rod dipped in dilute sulphuric acid until it turns distinctly red. Alkalies, alkaline earths, and their sulphurets, restore its blue color; alkaline carbonates and the soluble borates produce the same effect. Red litmus paper may also bo made by holding a strip of the blue litmus paper over a jar into which 2 or 3 drops of muriatic (hydrochloric) acid have been thrown.